by mikester »
Thu Mar 15, 2007 7:02 pm
You can get insulation boards from your local builders merchant that are for this. I think they are about 2inch thick but I don't see why you can't use more than one layer, just lay couple inches concrete or screed on the top. The boards double up as damp proofing (you will probably need some kind of DPM in the walls as well though. Can't remeber the name of the product I know Jewson sell it though.